1. Field of the Invention
The present invention relates to a digital input display apparatus into which digital video data is input, and more particularly relates to a display apparatus in which sampling is performed with a cycle different from that of the digital data input.
2. Description of the Related Art
With the rapid spread of digital pickup apparatuses (=image sensors) such as digital still cameras (DSC) and digital video cameras (DVC), small-size liquid crystal displays (LCD) have become commonly used as displays for such cameras, for which small sized displays capable of displaying very fine video images are desired.
FIG. 6 is a block diagram showing a structure of a typical conventional digital pickup apparatus comprising a pickup block 1, a digital signal processor (hereinafter, referred to as DSP) 2, a storage medium 3, a frame memory 4, an encoder 101, a digital-to-analog (hereinafter, referred to as D/A) converter 102, an analog signal processor (hereinafter, referred to as ASP) 103, and a display 9. The pickup block 1 includes, for example, a charge couple device (hereinafter, referred to as CCD) inside and outputs digital video data corresponding to a scenery received by the CCD. The DSP 2 performs predetermined processing such as gamma correction to a digital signal and outputs the processed digital video data to respective blocks. Moreover, the DSP 2 reads out video data from the storage medium 3 and the frame memory 4 and outputs it to the encoder 101. The storage medium 3 is, for example, a card having a built-in flash memory, a magnetic tape, or the like which stores video data that has been picked up. The frame memory 4 temporarily holds video data to be processed by the DSP (digital signal processor) 2. The encoder 101 converts the digital video data into a video format normalized by the NTSC, PAL, or the like. The D/A converter 102 converts digital data into analog data and outputs analog video data. The ASP 103 converts the video data into a voltage signal appropriate for the display 9 by again applying gamma correction to the analog video data and if the display 9 is an LCD, reversing the signal for reverse drive. The display 9 is a display apparatus such as an LCD and an EL display apparatus. For an active matrix display, the display 9 has a built-in H scanner 9a and a V scanner 9B and displays an image on a display block 9c corresponding to the video data of the pickup block 1 and the storage medium 3.
In recently introduced CCDs for DSCs and DVCs, the number of pickup pixels has rapidly increased. For example, it is now not uncommon for several millions of pixels to be arranged in matrix and pick up an image data based on a predetermined standard. However, in order to reduce the size of such a digital pickup apparatus, the number of pixels of the display 9 for displaying an image being picked up is normally about a hundred thousand. Moreover, as shown in FIG. 2A, image data picked up is usually arranged in the stripe arrangement in which colors RGB are aligned in the column direction while in the display 9, as shown in FIG. 2B, in order to display a highly fine image with a small number of pixels, the colors RGB are usually arranged in the delta arrangement, i.e., adjacent lines are offset with a predetermined pitch.
In such a case, sampling processing is required for thinning video data which is input, in accordance with the number of pixels of the display. In the conventional structure, digital video data is temporarily converted into analog data and the ASP (analog signal processor) 103 samples the analog video data at a predetermined a timing in accordance with the number of pixels of the display 9.
However, a circuit handling an analog signal usually has a bipolar transistor and designing of the circuit requires a long time as compared to a digital circuit consisting of an MOS transistor. Moreover, an analog circuit consisting of the bipolar transistor consumes more power than a digital circuit consisting of the MOS transistor.
Moreover, as is clear from comparison of FIG. 2A and FIG. 2B, when displaying stripe-arranged data on a delta-arrangement display, data in lines of odd numbers may be displayed as it is but in lines of even numbers, data pixel positions are different from the display pixel positions, which makes correct display impossible.